外文翻译--在开放CAM牙科系统基础上的国产5轴联动轮廓加工数控机床和工业CAM软件 英文版

696 J Huazhong Univ Sci TechnolMed Sci DOI 101007s115960110585y 3l(5)：696-7O0，2O11 An Open CAM System for Dentistry on the Basis of China-made 5-axis Simultaneous C ontouring CNC Machine Tool and Industrial CAM Software Li Lu(鲁莉) ，Shusheng LIU(刘树生) ，Shenggen SHI(施生根) ，Jianzhong YANG(杨建中) Department ofStomatology,Beijing Chaoyang Hospital Capital Medical University,Beijing 100000,China ：Beoing Shengwei Hongfi CNC Equipment Company Limited,Beijing 100002，China 306HospitalofPeoplesLiberationArmy,Beijing 10000China Engineering Center,Huazhong University ofSciences and Technology,Wuhan 430060,China Huazhong University of Science and Technology and Springer-Verlag Berlin Heidelberg 20 1 1 Summary：Chinamade 5-axis simultaneous contouring CNC machine tool and domestically devel oped industrial computer-aided manufacture(CAM)technology were used for ful1 crown fabrication and measurement of crown accurac with an attempt to establish an open CAM system for dental processing and to promote the introduction of domestic dental computer-aided design fCAD)CAM systemCommercially available scanning equipment was used to make a basic digital tooth model after preparation of crown，and CAD software that comes with the scanning device was employed to design the crown by using domestic industrial CAM software to process the crown data in order to generate a solid model for machining purposeand then Chinamade 5一axis simultaneous contouring CNC machine tool was used to complete machining of the whole crown and the intemal accuracy of the crown intema1 was measured by using 3DMicroCTThe results showed that Chinamade 5-axis simultaneous contouring CNC machine too1 in combination with domestic industrial CAM technol ogy can be used for crown making and the crown was well positioned in dieThe intemal accuracy was successfully measured by using 3DMicroC It is concluded血at an open CAM system for den tistry on the basis of Chinamade 5-axis simultaneous contouring CNC machine tool and domestic industrial CAM software has been establishedand development of the system wil1 promote the in troduction of domesticallyproduced dental CADCAM system Kev words：computer-aided dental design and manufacture；fiveaxis simultaneous contouring CNC machine tool；CAM software；open dental CAM system With the improvement of 1iving standardsthe de mand on dental prostheses has been on rise in China Computeraided design(CAD)and computer-aided manufacture(CAM)technologies， iointly called CADCAMwhich used to be widely applied in indus trial automation and aerospace field in 1 970s，were Successfully introduced into the fabrication of dental prostheses since 80s of 1ast centuryThe application of the technology in clinical practice substantially shortens treatment time，reduces the prices of dental restorations， and improves the results of dental restoration in terms of appearance，accuracy and suitability Compared with the application of CADlCAM tech nologies in other industrial fieldsso far CADCAM technologies for dentistry remain at an interim stage and still have a long way to go to sarisfy the demand of clinicians and patientsMoreover，in China，most hos Li LUEmail：dentist1uligmail，corn Corresponding author，shishengensohncom The research was supposed by a grant from the PLA Pro gram for Clinical Hightech Projects for Military Hospitals (No20 1 0GXJS053) pitals cant afford imported CADCAM systems and solution to the problem is the in仃oduction of domesti callydeveloped systemsSome Chinese scholars such as Lu et al have been working on the research and de velopment of CADCAM for dental prostheses and have made some encouraging achievementsUp to now， however，there have been no industrialized domestic CADCAM systems in China In this study，our research group，teaming up with Wuhan Centra1 China CNC Engineering Center and Beijing Shengwei Hongji cNc Equipment CoLtd Chinaemployed a domestically-made industrial CAM system and a Chinamade 5axis simultaneous contour ing CNC machine tool to process artificial crown and tested the adaptation of the artificial crown by using Micro CTwith an attempt to promote the introduction of domestic CADCAM system in China 1 MATERIALS AND METHoDS 11 Materials 3Shapes Dental System 2009 scanner，with a builtin dental CAD software，was products of 3 shape AS Co，DenmarkCAM software package(Central 698 JHuazhongUniv SciTechnolMed Sci31(5)：2011 prosthesis，Strub et al believe that this open mode will find wider application in the futureL CADCAM is a universal coneeDt in the equipment manufacturing industryand the broad prospect of denta1 CADCAM processing system has aRracted the attention of many machine tool manufacturers and software sup plierswhile the denta1 CADCAM system going open makes it possible for the indus仃ia1 machine tools and CAM software to be used in dental CADCAM system OPENMINDa German software supplier has developed an open intelligent programming system called Hyper DENT which has allowed digita1 dental models to be closely Iinked uD with digital highprecision machining The company has also developed a specia1 cutting tool used in highperformance machining center for dental prosthesis processBritish Delcam Plcthe worlds leading professiona】CADCAM software company has also launched its latest version of dental software system DentCAD and DentMILLThe worldfamous indus仃ial machine tool manufacturerRoeders fGermany)and the machine tool manufacturer DMG have developed ad vanced machining technologies such as ultrasonic proc essing technology for dental industtial machine tools making CNC machining for dental CADfC M system more specialized The multiaxis industrial machine tools emerged from the aviation industry and have the advantages of higher poweref五ciencyaccuracy and adaptability etc Compared with the仃aditiona1 dental CAM processing cellsthe industrial machine tools can machine wider range of materials and process all materials used in den tal prostheses at presentMoreover，they are more versa tile，with ability to machine not only the crown and prosthesis for fixed bridge etcbut also some implanta tion objectsIntracoronal and extracoronal precision at tachments and other components can not be made by the traditional CAM machining cells for dental prostheses Application of indus仃ial machine tools in dental prosthesis CAM system can also make the dental pros thesis processing go industrialized，thereby improving the efhciency of dental prosthesis processingreducing processing and equipment-related costs and tapping so- cial resources more effectively 32 Advanced Features of the Five-axis Simultaneous Contouring Machining in the Dental CADCAM Sys tem Possessing Despite the in仃oduction of the rapid forming tech nology into the machining cell of dental CADCAM sys tem，currently，mainstream machining form remains CNC multiaxis simultaneous contouting curing The representative three-axis simultaneous con- touring machining system is inLab(Sirona，Germany)， and it can only machine along one axial direction，so its axia1 line of the curer is not consistently in alignment with the curvature in vector direction，and due to the di- ameter size of the curer；some parts of workpiece are undercut and some overcutTherefore，the finished surface formed by threeaxis machining is only approxi- mate to curved surfaceThe system is hi曲ly emcient when used for the restorations of simple formsIt is in expensive and easy to use，but its accuracy is low and cutter WOrks along only one directionFour。axis slmuI。 taneous contouring machining 1s represented by乞end (Wieland-ImesGermany)and it is equipped with an additional rotary axis on the basis of threeaxis simulta neous contouring system，which allows the machining of the whole crown upon one clampingMoreover, four-axis simultaneous contouring machining can achieve better curing conditions with the processing of some internal surfaces by rotating workpiece so as to reduce profile errorHowever，compared with fiveaxis simultaneous contouring machining，the tool axis direc tion is not in line with the vector direction of curved sur face in most cases，and the processing is still an ap proximationIn comparison with the three-axis simulta neous contouring machining，the fouraxis simultaneous contouring machining is materialand auxiliary time-saving，while its accuracy of profile contouring machining accuracy is not high and it was unable to han die concaved surfaceFiveaxis machining is represented by Everest Engine of KaVo and ESPE Lava CNC 500 of 3MIt adds a swing axis to the system on the basis its fouraxis cotmterpartsThe tool axis is consistent with the reference vector at any points on the curved surface during machining，so its possible to precisely machine the profile of curved surface by selecting cutting tool of proper diameter to improve the machining accuracy of free space curved face machining efficiency and processing quality 11Therefore it can work with a wider range of machining and aRain higher processing e衔ciency and machining accuracy【 At presentfew dental CADCAM systems use fiveaxis simultaneous contouring technology，and the fiveaxis machining technology when used in the dental CADCAM system has a number of advanced featuresActually，when some fiveaxis machine tools are used for prosthesis machining threeaxis machining is adopted for rough finishing to achieve higher machining emciencywhile fiveaxis machining is used during finishing stage in order to at tain high machining accuracy and beRer processing qual ity 3-3 Accurate Assessment of Crown Accuracy by Us ing MicroCT for the Improvement of Machining Tool Denture processing requires that accuracy be 005 rain，and at present，the positiona1 accuracy of most CNC machine tools(with trave1 range within 500 ram)made by the machinery manufacturing industry is 00 1 2 mm and repeatability 0008 mm(according to ISO2302 standard)They can fully meet the reauiremems of den mre processingThe point is that this accuraucy refers to a static accuracy，not me m ining accuracy，and aboVe all，not the profi1e accuracVl J Until nOwno evaluation criteria are available f_0r the prOfile accuracV of cur、，ed surf_aces in machine tool industrvThe reasOn is that mere are nO ef-fective meas uring means f0r the accurate measurement Of me pro6le of smal1sized free cued surrace of sma11sizeWith conVentiona1 measuring means，the contact。type probe can achieVe much higher measuring accuracy，which is generally 0002 mmThe pr0blem is the probe diamete薹 ends to exceed 1 nunwhich m kes it unsuitab1e fl0r the intemal measurement of dental crown0n the other hand， the noncontact measurement general1y adopts 1ine laser scanning and its measuring accuracy is 00 1 5 mm，which is in the same accuracv c1ass of the measured obiect and is nOt suitable for me measurementl刚 JHuazhongUniv SciTechnolMed Sci31(5)：2011 699 Another reason for its difficult measurement of the denture machining accuracy is that，after processing，the crown can only be measured when it is set into the working space between natural toothsThe purpose of the measurement is to evaluate the adaptation，which is different from the measurement against the benchmark of machinery industryYet，the routine measurement evaluation standard is not applicable The commonly used methods for the detection of the internal accuracy of crown include impression-rep- lica and crosssection methodsImpressionreplica tech nique has a number of versionsIn the recent years，some scholars used silicon rubber impression in combination with Photoshop software package to evaluate the adaptability of prosthesisThe method is 1imited in that itww1vwv can not gi e aprecise quantification of the g印size17 With crosssection methodthe prosthesis is wrapped and embedded after being fixed(by gluing)on a base die， and then the prosthesis cut from different directions to measure the margina1 fit and the thickness of the cement under a stereo microscope【 The disadvantage of this method lie in that it is destructive to the castings and the die and may cause the deformation of prosthesis Micro CT technologybased on microfoCUS Xray imagingis a nove1 3D imaging technology with su perhigh resolutionHighprecision 3D images exhibiting detailed information within the samples can be obtained without damaging the samples【 In this study 3DMicroCT is employed to measure the adaptation of the crown to die on the crosssection after the crown was put into the dieThis approach not only solves the prob 1em with the measurement of the adaptation between the denture and the die，but also provides the characteristic dimensions of the crown crosssection，which allows machine tool designers to make accurate evaluation on the profile accuracy to work out better machine tools McLean et al proposed that clinically the acceptable edge gaD should be 1 20 gm，but some researchers be一 1ieve that an internal gaD in the range of 200-300 gm is acceptableNevertheless，so far，there is still no scientific evidence supporting these suppositions zzResearches 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